• Journal of Environmental Science International
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• v.21 no.5
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• pp.555-562
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• 2012

The experimental determination of equilibrium constants is required to estimate concentrations of reagents and/or products in environmental chemical reactions. For an example, the choice of copper (Cu) complexation reactions was motivated by their fast kinetics and the ease of measurement of Cu by an ion-sensitive electrode. Each individual titrant of sulfate ($SO{_4}^{2-}$) and oxalate ($C_2O{_4}^{2-}$) was expected to have its own unique characteristics, depending on the bonding in Culigands connected to the aqueous species. The complexation reaction of Cu with $SO{_4}^{2-}$ somewhat fast reached equilibrium status compared with $C_2O{_4}^{2-}$. The experimental equilibrium constants ($K_{eq}$) of copper sulfate ($CuSO_4$) and copper oxalate ($CuC_2O_4$) were determined $10^{2.2}$ and $10^{3{\sim}4.3}$, respectively.

• Proceedings of the PSK Conference
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• 2003.10b
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• pp.147.2-147.2
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• 2003

A fast and matrix-assisted laser desorption/ionization-mass spectrometry compatible protein staining method in one- and two-dimensional sodium dodecyl sulfate-polyacrylamide gel electrophoresis is described. It is based on the counterion dye staining method that employs oppositely charged two dyes, Zincon and Ethyl Violet to form an ion-pair complex. It is safe to use since the methanol used previously in staining solution was replaced with ethanol, which is not toxic. The protocol including fixing, staining and quick washing steps can be completed in 1 to 1.5 h depending upon gel thickness. (omitted)

• Journal of the Institute of Electronics Engineers of Korea SC
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• v.37 no.4
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• pp.49-54
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• 2000

A new functional organic thin film optical waveguide ion sensor is designed, which can select a specific ion, i.e., $Ca^{2+}$ -ion. The sensing membrane was composed of PVC-PVAC-PVA copolymer matrix based on anionic cation-selective chromoionophor(ETH5294), neutral ionophore(K23El), anionic site and plasticizer and it was coated on the etched glass substrate as embeded type optical waveguide itself. The sensor sensitivity dependence on waveguide length and thickness, contence of chromoionophore, and each mode was investigated. And this sensor could detect $Ca^{2+}$ ion in concentrations ranging from 1$\times$10­6~1M(with 0.05M tris-HCI buffer solution of pH7.4) by measuring the absorbance change at 514nm of light. Utilizing thin film membrane, the fast response time and high sensitivity are obtained. Also, it is expected that this sensor can be applied to various biochemical important ions.ons.

• Applied Chemistry for Engineering
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• v.30 no.6
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• pp.737-741
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• 2019

A low-cost and flexible potassium ion (K⁺) sensor was fabricated through a screen-printed process. Uniform and conformal coating of conductive inks was verified by scanning electron microscopy and optical microscopy measurements. The K⁺-sensors showed a high sensitivity, fast response time, and low detection limit. The sensitivity of K⁺-sensor was similar to that of both mechanically normal and bent states. The K⁺-sensor exhibited a good reproducibility with no hysteresis effect and excellent long term stability. In addition, the K⁺-sensor showed an excellent selectivity for K⁺ concentrations in the presence of other interfering cation ions. Successful measurements of K⁺ concentrations in sports drink samples were demonstrated by comparing K⁺ concentration values from K⁺-sensor to those of using a commercial K⁺-meter.

• Bulletin of the Korean Chemical Society
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• v.29 no.4
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• pp.790-794
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• 2008

Nucleophilic addition reaction of benzenethiols (PhSH) to 1-(2-nitrovinyl) benzenes ($\beta$ NS) in the presence of triethylamine (TEA) has been studied in acetonitrile at 25 ${^{\circ}C}$. The rate is first order with respect to [PhSH], [TEA] and [$\beta$ NS]. The reaction is found to proceed with the formation of ion-pair between benzenethiol and TEA. A suitable mechanism with the formation of an adduct between ion-pair and substrate in a slow step followed by its rearrangement to 1,2-addition product in a fast step has been proposed and corresponding rate law derived. From the rate law, the rate constants for the interaction between ion-pair and $\beta$NS have been evaluated. Interestingly, in both para-substituted substrates and benzenethiols the rate increases with the electron-withdrawing power of the substituents. The positive sign of $\rho_x$ in benzenethiols has been explained. The magnitude of cross-interaction constant, $\rho_{xy}$ is small (0.08). The magnitude of the Hammett $\rho_x$ values is higher than that of the Bronsted, $\beta_x$ values for benzenethiols. The kinetic isotope effect, $k_H/k_D$, is found to be greater than unity. A suitable transition state with simultaneous formation of $C_\beta$ -H and $B_\alpha$ -S bonds involving the ion-pair and $\beta$NS in a single concerted step has been proposed to account for these observations.

• Applied Chemistry for Engineering
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• v.19 no.3
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• pp.304-309
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• 2008

Cryptand series ion exchange resins were synthesized with 1-aza-12-crown-4 macrocyclic ligand attached to styrene (4 series dangerous matter) divinylbenzene (DVB) copolymer with crosslink of 1％, 2％, 4％ and 8％ by a substitution reaction. The synthesis of these resins was confirmed by content of chlorine, element analysis, electron micrograph, and IR-spectrum. The effects of pH, time, dielectric constant of solvent and crosslink on adsorption of uranium (${UO_2}^{2+}$) ion were investigated. The uranium ion showed a fast adsorption on the resins above pH 3. The optimum equilibrium time for adsorption of metallic ions was about two hours. The adsorption selectivity determined in ethanol was in increasing order uranium (${UO_2}^{2+}$) > nickel ($Ni^{2+}$) > gadolinium ($Gd^{3+}$) ion. The adsorption was in order of 1％, 2％, 4％, and 8％ crosslinked resin and adsorption of resin decreased in proportion to order of dielectric constant of solvents.

• Applied Chemistry for Engineering
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• v.34 no.5
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• pp.556-565
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• 2023

Fast industrial and agricultural expansion result in the production of heavy metal ions (HMIs). These are exceedingly hazardous to both humans and the environment, and the necessity to eliminate them from aqueous systems prompts the development of novel materials. In the present study, a UIO-66 (COOH)₂ metal-organic framework (MOF) containing free carboxylic acid groups was post-synthetically modified with L-glutamic acid via the solid-solid reaction route. Pristine and glutamic acid-treated MOF materials were characterized in detail using several physicochemical techniques. Single-ion batch adsorption studies of Pb(II) and Hg(II) ions were carried out using pristine as well as amino acid-modified MOFs. We further examined parameters that influence removal efficiency, such as the initial concentration and contact time. The bare MOF had a higher ion adsorption capacity for Pb(II) (261.87 mg/g) than for Hg(II) ions (10.54 mg/g) at an initial concentration of 150 ppm. In contrast, an increased Hg(II) ion adsorption capacity was observed for the glutamic acid-modified MOF (80.6 mg/g) as compared to the bare MOF. The Hg(II) ion adsorption capacity increased by almost 87% after modification with glutamic acid. Fitting results of isotherm and kinetic data models indicated that the adsorption of Pb(II) on both pristine and glutamic acid-modified MOFs was due to surface complexation of Pb(II) ions with available -COOH groups (pyromellitic acid). Adsorption of Hg(II) on the glutamic acid-modified MOF was attributed to chelation, in which glutamic acid grafted onto the surface of the MOF formed chelates with Hg(II) ions.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.24 no.2
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• pp.133-138
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• 2024

Lithium-ion batteries are used in many fields due to their high energy density, fast charging conditions, and long cycle life. However, overcharging, over-discharging, physical damage, and use of lithium-ion batteries at high temperatures can reduce battery life and cause damage to people due to fire or explosion due to damage to the protection circuit. In order to reduce the risk of these batteries and improve battery performance, the characteristics of the charging and discharging process must be analyzed and understood. Therefore, in this paper, we analyze the charging and discharging characteristics of lithium-ion batteries using a battery charger and discharger and simulator to reduce the risk of loss of life due to overcharge and overdischarge, as well as casualties from fire and explosion due to damage to the protection circuit.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.38 no.2 s.115
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• pp.9-15
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• 2006

Neutral sizing is required for linerboard to solve the troubles in strength and process caused by recycled raw materials. AKD sizing efficiency can be influenced by process condition like white water quality, fines retention and so on. Therefore, this study was aimed to evaluate sizing performance of general and fast cure type AKDs using process water obtained from linerboard mill. To evaluate effect of process water quality on AKD sizing, white water was diluted with tap water at the different dilution ratios and UKP slurry was sized using the prepared water. Also, effects of inorganic and organic ion material on sizing were examined. When white water was used for stock forming, UKP sheet showed very low sizing degree. Sizing degree of sheet was increased with increase of dilution ratio because water quality was improved. Especially anionic organic material had a greater influence on AKD sizing than inorganic material. When white water quality was deteriorated, fast cure type AKD showed superior sizing performance to general type AKD.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05d
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• pp.413-418
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• 1996

To derive the optimimum antenna launching condition for fast wave current drive, the propagation and absorption of the ion cyclotron range of frequencies waves are studied in a KT-2 tokamak plasma. We sove the kinetic wave equation in one dimensional slab geometry with the phase-shifted antenna array to inject the toroidal momentum to electrons. The accessibility conditions and the guidelines of the optimum antenna design for the efficient current drive are derived. The dependence of the current drive efficiency on launching conditions such as the phase and spacing Is presented.